NATIONAL SENIOR CERTIFICATE GRADE 12 PHYSICAL SCIENCES: CHEMISTRY (P2) COMMON TEST JUNE 2014

Transcription

1 Physica Science/P2 1 June 2014 Common Test MARKS: 100 TIME: 2 hours NATIONAL SENIOR CERTIFICATE GRADE 12 PHYSICAL SCIENCES: CHEMISTRY (P2) COMMON TEST JUNE 2014 This question paper consists of 10 pages and a 4 Data Sheets. *PHSCE2*

2 Physica Science/P2 2 June 2014 Common Test INSTRUCTIONS AND INFORMATION 1. Write your name in the appropriate spaces on the ANSWER BOOK. 2. Answer ALL the questions in the ANSWER BOOK. 3. This question paper consists of TWO sections: SECTION A (14) SECTION B (86) 4. You may use a non-programmabe cacuator. 5. You may use appropriate mathematica instruments. 6. Number the answers correcty according to the numbering system used in this question paper. 7. Data sheet and periodic tabe are attached for your use. 8. Give brief motivations, discussions, et cetera where required.

3 Physica Science/P2 3 June 2014 Common Test SECTION A QUESTION 1: MULTIPLE CHOICE QUESTIONS Four options are provided as possibe answers to the foowing questions. Each question has ony ONE correct answer. Write ony the etter (A D) next to the question number ( ) in the ANSWER BOOK. 1.1 The IUPAC name for the foowing compound is H H C H H H H H H H C C C C C C H H H H H H C H H C H H H C H H A 2,2,5-trimethyheptane. B 3,6,6-trimethyheptane. C 2-ethy-5,5-dimethyhexane. D 5-ethy-2,2-dimethyhexane. (2) 1.2 Consider the reaction represented beow: C 12 H 26 2C 5 H 10 + C 2 H 6 The term that best describes this reaction is A eimination. B addition. C cracking. D poymerisation. (2) 1.3 A change in enthapy is caed A activated compex. B heat of reaction. C activation energy. D externa energy. (2)

4 Physica Science/P2 4 June 2014 Common Test 1.4 The foowing chemica equation represents a reaction that occurs when soft drinks are carbonated: CO 2 (g) + H 2 O() H 2 CO 3 (aq) Which statement is TRUE when this reaction is at equiibrium in a cosed system? A The decomposition of H 2 CO 3 (aq) begins. B The formation of H 2 CO 3 (aq) stops. C The formation of H 2 CO 3 (aq) stops, and the decomposition of H 2 CO 3 (aq) begins. D The rates of formation and decomposition of H 2 CO 3 (aq) are equa. (2) 1.5 Refer to the foowing equation: NH 3 (g) + H 2 O() NH 4 + (aq) + OH - (aq) The two BrØnsted-Lowry bases in the reaction equation are: A NH 3 and H 2 O B NH + 4 and OH - C + H 2 O and NH 4 D NH 3 and OH - (2) 1.6 Which of the foowing substance(s) is/are amphiprotic? (i) H 2 PO 4 - (ii) H 3 PO 4 (iii) HPO 4 2- A (i) B (iii) C (ii) and (iii) D (i) and (iii) (2) 1.7 Which of the foowing statements regarding a catayst is TRUE? A It changes the heat of a reaction. B It reduces the energy of the activated compex. C It decreases the energy of the reactants. D It increases the number of moes of products formed. (2) TOTAL SECTION A: 14

5 Physica Science/P2 5 June 2014 Common Test SECTION B INSTRUCTIONS 1. Start EACH question on a NEW page. 2. Leave ONE ine between two subquestions, for exampe between QUESTON 2.1 and QUESTION Show the formuae and substitution in a cacuations. 4. Round off your fina numerica answers to a minimum of TWO decima paces. QUESTION 2 The etters A to F in the tabe beow represent six organic compounds. A Methy ethanoate B H H H H C C C C H H H O H C H H H H C C C C H H H H O D H H O H C C C O H H H E CH 3 CH 3 C CH 2 CH 3 O H F ( CH 2 CH 2 ) n 2.1 Write down the: Name of the homoogous series to which compound D beongs. (1) IUPAC name of compound C. (1) Structura formua of monomer of compound F. (2) 2.2 Compound E represents an acoho. Cassify this acoho as primary, secondary or tertiary. (1) 2.3 Briefy expain why compounds B and C are cassified as FUNCTIONAL ISOMERS. (2) [7]

6 Physica Science/P2 6 June 2014 Common Test QUESTION 3 The tabe beow shows the boiing points for some hydrocarbons. COMPOUND A CH 3 CH 3 C CH 3 CH 3 B CH 3 CH 2 CH CH 3 CH 3 BOILING POINT ( C) 9 28 C CH 3 CH 2 CH 2 CH 2 CH What are hydrocarbons? (1) 3.2 Consider the boiing point of the compounds in the above tabe Describe the trend in the boiing points. (1) Expain this trend in terms of the strength of intermoecuar forces and energy. (3) 3.3 Which compound, A, B or C wi have the highest vapour pressure? (1) [6] QUESTION You are provided with a sampe of butan-1-o Write down the condensed structura formua of this compound. (2) You are required to convert butan-1-o to butan-2-o. Show, by means of a sequence of reaction steps using condensed structura formua, how this can be achieved. Indicate the reagents and reaction conditions for each step of the reaction sequence. (4) 4.2 Hydroysis and hydration are two types of organic reactions with the same organic product What is the organic product of these reactions? (1) Write down, using condensed structura formua, an exampe of a hydration reaction. Indicate the reaction conditions. (You may use any organic compound of your choice). (3) Write down, using condensed structura formua, an exampe of a hydroysis reaction. Indicate the reaction conditions. (You may use any organic compound of your choice). (3) [13]

7 Physica Science/P2 7 June 2014 Common Test QUESTION 5 The contact process is used to prepare suphuric acid in the high concentrations needed for industria purposes. This process invoves the oxidation of suphur dioxide in the presence of a vanadium (V) oxide catayst: 2SO 2 (g) + O 2 (g) 2SO 3 (g) Use the reaction and the graph, where appicabe, to answer the questions that foow. 5.1 Is the forward reaction exothermic or endothermic? Prove your answer by cacuating the vaue of H for this reaction. (2) 5.2 What is the activation energy for the forward reaction in the absence of the anadium(v) v oxide catayst? (1) 5.3 The graph indicates that 1580 kj.mo -1 is needed to break the bonds in the SO 2 (g) and O 2 (g) moecues. How much energy is reeased when the new bonds in the SO 3 (g) moecues form? (1) 5.4 Determine the activation energy for the REVERSE REACTION in the presence of the vanadium(v) oxide catayst. (1) [5] QUESTION 6 The grade 12 teacher investigates one of the factors that affect the rate of reaction. In Experiment 1, 5 g zinc granues are added to 50 cm 3 of 0,3 mo.dm -3 hydrochoric acid. In Experiment 2, 5 g zinc powder is added to 50 cm 3 of 0,3 mo.dm -3 hydrochoric acid. For both experiments the voume of hydrogen gas produced is measured every 10 seconds. 6.1 Write down a baanced equation for the reaction taking pace. (3) 6.2 Name the factor affecting the rate of reaction that is investigated here. (1) 6.3 Why shoud the teacher ensure that equa masses of zinc are used in each experiment? (1)

8 Physica Science/P2 8 June 2014 Common Test 6.4 Hydrochoric acid in both experiments is in excess. Give a reason why the excess hydrochoric acid in both experiments does not infuence the resuts. (1) The teacher asks earners to draw the graph using the resuts obtained in Experiment 1. The earners use the resuts in Experiment 1 to draw the graph beow. 6.5 Cacuate the average rate of the reaction between the 20 th and 40 th second. (3) 6.6 How wi the average rate of the reaction between the 20 th and 40 th second in Experiment 2 compare with that in Experiment 1? Write down ony GREATER THAN, LESS THAN or EQUAL TO. (1) 6.7 Use the coision theory to expain your answer in QUESTION 6.6. (2) Experiment one is repeated, but this time a few sma pieces of copper are added to the reaction vesse. 6.8 How wi this affect in the foowing, when compared to experiment one? (Write down ony INCREASES, DECREASES or REMAINS THE SAME.).8.1 6Voume of hydrogen gas produced (1).8.2 6The gradient of the graph (1) 6.9 Expain your answer to QUESTION above. (2) [16]

9 Physica Science/P2 9 June 2014 Common Test QUESTION 7 Consider the foowing reversibe reaction in a seaed container: H 2 (g) + I 2 (g) 2HI (g) The experiment was done three times under different conditions. In each case 1 g H 2 and 127 g I 2 reacted in 2,0 dm 3 container. The sketch graphs of concentration versus time for the three investigations are shown beow. Graph A was obtained at 500 C. Graph B was obtained at 600 C, but under the same conditions as graph A. Graph C was aso obtained at 500 C but under different conditions as graph A. 7.1 Is the above reaction an exampe of homogeneous or heterogeneous equiibrium? Give a reason for your answer. (2) 7.2 What factor is responsibe for the difference between graph A and graph C? (1) 7.3 Give an expanation for the answer to QUESTION 7.2 with reference to the graph.(2) 7.4 Is the reaction in this experiment exothermic or endothermic? (1) 7.5 Use Le Chateier s principe to give an expanation for your answer to QUESTION 7.4. (2) 7.6 Use the suppied information to cacuate the equiibrium constant at 500 o C. (8) [16]

10 Physica Science/P2 10 June 2014 Common Test QUESTION 8 The foowing soutions are provided: Soution A: 0,1 mo.dm -3 H 2 SO 4 Soution B: 0,1 mo.dm -3 HC Soution C: 0,1 mo.dm -3 Na 2 SO 4 Soution D: 0,1 mo.dm -3 Na 2 CO 3 Soution E: 0,1 mo.dm -3 NaOH 8.1 Use the symbos A, B, C, D or E to indicate the soution that: may have a ph = 7 (1) has the highest concentration of H 3 O + (1) is a strong base (1) is a monoprotic acid (1) 8.2 Cacuate the ph of soution A (assuming the temperature of the soution is 298 K).(3) 8.3 When a piece of itmus paper is paced in soution D, it turns bue. Write down the equation for the reaction of this compound (D) with water that expains this observation. (3) [10] QUESTION 9 A grade 12 earner finds some suphuric acid (H 2 SO 4 ) soution in a botte abeed diute suphuric acid. The earner wishes to determine the concentration of the suphuric acid soution. To do this the earner decided to titrate the suphuric acid against a standard potassium hydroxide (KOH) soution. 9.1 What is meant by a diuted acid? (1) 9.2 What is a standard soution? (1) 9.3 Cacuate the mass of potassium hydroxide which the earner must use to make 300 cm 3 of 0,2 mo.dm -3 KOH soution. (4) During the titration the earner finds that 15,04 cm 3 of the KOH soution neutraises 20,15 cm 3 of the H 2 SO 4 soution. The equation for the reaction is 2KOH (aq) + H 2 SO 4(aq) K 2 SO 4(aq) + 2H 2 O () 9.4 What is the importance of adding an indicator during titration? (1) 9.5 Which ONE of the indicators isted in the tabe beow is most suitabe to use during this titration? Expain your choice. (2) Indicator Methy orange 2,9 4,0 Bromothymo bue 6,0 7,6 Phenophthaein 8,3 10,0 ph range 9.6 Cacuate the concentration of the H 2 SO 4 soution. (4) [13] TOTAL SECTION B: 86 GRAND TOTAL: 100

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